Experience

* More than 30 years designing and building modern launches
* More than 30 years repairing and maintaining modern launches
* Countless internal and external refits
* Hull extensions on a wide range of launches
* Repowered a large number of modern launches

Illustrative Case History on a Modern Launch

Dixie is a 65ft. plywood construction planing launch which comes to Robertson Boats for maintenance, servicing and the odd jobs that the owner wants done.

This particular visit the owner wanted to make the deadwood keel deeper and change the exhaust system. He explained to the management what changes were to be made and they talked about the various options and ideas they all had before coming to a decision.

The keel extension was going to be a straight forward job requiring an addition of 500mm. It was to be constructed out of 2”x 150mm hardwood planks laminated together with epoxy and then glued and through bolted to the original keel. A pattern was made of the shape the extension was to take and the hardwood planks were then ripped up, cut to length and dressed. They were then laminated together in the workshop.

While the lamination was going off the keel batten was removed from the existing keel and the surface was then cleaned up and prepped for the attachment of the extension. The holes were then drilled through the existing keel for the through bolts. The glue in the lamination had gone off by now so the small amount of shaping required to the extension was done. It was then placed upside down and sheathed in double bias fibreglass. Now the extension was taken to be fitted to the boat. It was put in place and propped up in position to hold it to the boat and the join at the top was clamped to stop it moving. Everything was plumbed up and checked over before the holes in the existing keel for the through bolts were extended through the extension.

The extension was then removed and the glue was applied to the surfaces before it was put back in place and everything was bolted together. Now the join was tabbed over with double bias fibreglass to reinforce it and it was then bogged out and faired up. A hard wood keel batten had been machined up and was fitted to the bottom of the keel and resin sealed.

The painters came and coated the extension in epoxy primer. The primer was then keyed up and the antifouling was applied. The exhaust system was to be changed from where it exited the boat at amidships to exit further aft at the transom. Instead of running exhaust hose through the interior of the boat to the transom they decided to construct a cowling out of plywood and fibreglass from the original outlet along the boat to the transom.

A plan was drawn up and they got to work cutting the required lengths of ply for the cowling. The ply was then epoxy glued and screwed together in the workshop and the corners were coved out to strengthen them before being heavily fibreglassed inside and out. Once the fiberglass had gone off the inside of the cowlings were epoxy gelcoated.

While that was taking place the engineers had been busy up in the boat removing the original exhaust system. The new fibreglass mufflers and risers were installed, they ran out through the hull and were glued and fibreglassed in place. The engineers then hooked the new system up to the engines.

Next the surface of the boat was prepped for the attachment of the cowlings. The hull was stripped back to good, clean wood along the area that was to be glued so that a good bond could be achieved. The cowlings were then taken to the boat and dry fitted to check that there was the right amount of fall to prevent water pooling in them before being glued in place.

It was then tabbed with fiberglass onto the hull and the whole thing was bogged out. The bog was faired up and the painters sprayed over it with epoxy primer to seal it up and build up a good protective base. It was then guide coated and blocked back smooth before being thoroughly cleaned up ready for finish coating.

The finish coat was sprayed on and blended into the rest of the paint work. A high quality finish was obtained and the new exhaust cowlings looked like they were always part of the boat. The boat was launched and taken for a sea trial, it performed well with the new keel and the new exhaust system and the owner was happy.